The construction of roads and plazas as well as, for example, airport runways normally starts with a smoothing and compacting of the surface area to be paved. To the surface area thus prepared a road paver then applies the paving material to be paved by spreading it across its entire working width, smoothing it and precompacting it. The road paver is in most cases followed by one or more rollers, for example tandem rollers or single-drum rollers, which are used to further compact the layer paved by the road paver. During this process, the thickness of the paved layer continuously decreases until an optimum degree of compaction has been reached at which the finished road or plaza or runway has a maximum life span or service life. When constructing roads, plazas and runways, strict specifications regarding the required minimum layer thickness must typically be met. At the same time, the cost of the paving material, of which normally several tons are required, represents a decisive factor for the profitability of the corresponding construction project. It is thus necessary to meet the minimum requirements regarding the layer thickness as precisely as possible in order to avoid implementing unnecessary amounts of paving material.
It is, however, difficult to determine the actual layer thickness of the paved material after compaction. For example, until now, the thickness of the layer left behind by the road paver has been measured at the levelling cylinders of the paving screed of the road paver. However, this layer, which is merely precompacted, is compacted further by the road rollers that follow, so that the layer thickness decreases further. An exact determination of the actual thickness of the paved layer is thus not possible until the last roller has passed over it. Existing manual methods for determining the layer thickness are, however, complicated, time-consuming and expensive.